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There’s an old myth that charging our smartphones overnight after they’ve reached full-capacity is somehow damaging to their batteries — but this is simply not the case. Typical smartphone batteries are designed to last around a year and a half, or about 400 full cycles before their capacity begins gradually eroding; so fears about charging a battery after it’s fully charged are largely overblown. In fact, according to a report from Business Insider, what’s more likely to lead to a battery’s decline is how far we push our phones in everyday usage.
“Having your phone plugged in at night doesn’t diminish the battery,” says Kyle Wiens, head of iFixit, a firm best known for its exhaustive device tear-downs and repair guides. “It’s all about cycle count — it’s all about how you actually use the battery, how much work you’re making the battery do.”
In terms of ‘cycle counts’ in relation to battery performance and long-term decay, Wiens added that it’s not about how many times a day you plug-in and unplug your device from a power source, but rather the number of times it reaches full capacity. For example, charging your iPhone with 10% battery up to 60% would constitute a ‘half-cycle’ — or 50% of a full, 0-100% charge.
“In terms of the gradual erosion of battery life, what must be understood is that phone batteries are constantly in a state of decay,” said a representative with battery and charger accessory-maker, Anker, who added that “Sleeping with a phone charging overnight will make no noticeable difference in the process.”
Tips for Overnight Charging
Thanks to modern advancements in battery technology, most smartphones are designed to significantly reduce their draw current once their batteries have reached 100% capacity. This is worth noting for two reasons: one, if you’re like most people, you charge your smartphone while you’re asleep, and two, because you’re likely not going to wake up in the middle of the night just to unplug it once it’s reached full capacity.
What’s definitely worth worrying about is the temperature of your device and where you place it. Since battery charging is a heat-inductive mechanism, your smartphone will heat up substantially while it’s plugged in. And therefore, while it may be convenient or perhaps even comforting to sleep with your smartphone beside you, it’s worthwhile to ensure you’re not smothering it with your pillow or blanket. By doing so, you won’t have to worry about factors like overheating and potentially damaging your device’s internal components.